while(<*.html>) {
    $oldname = $_;
  open(OLD,"<$oldname")
      || die "Can't open input file $oldname $!";
    s/\.html$/\.new/;
    $newname = $_;
  open(NEW,">$newname") 
      || die "Can't open output file $newname $!";
    while(<OLD>) {
	s/gopher/World Wide Web/gi;
	print NEW; }
    close(OLD);
    close(NEW);
    $backupname = $oldname;
    $backupname =~ s/\.html$/\.bak/;
  unlink $backupname
      || die "Can't delete old backup file $backupname $!";
  rename $oldname, $backupname
      || die "Can't rename $oldname to $backupname $!";
  rename $newname, $oldname
      || die "Can't rename $newname to $oldname $!";
}